Jerry, this is the way to go for some of your big projects! I don't load tracks anymore, I use GPX2img pretty much all the time now.

You could put ALL of SMTS (or GWT, or Mex2Can, or even ALL of your track files together) on a single map overlay. Then load it onto the uSD card in your GPS along with R&R. Then copy that IMG file to other uSD cards or post that map file on the internet for anyone to copy themselves. Call it "Coundown's map to the World"!

My guess is such a SUPER map would load just fine into just about any Garmin, including Nuvi and Zumo.